Automatic landing brake for aeroplanes



Sept. 10, I929.

L. BREGUET AUTOMATIC LANDING BRAKE FOR'AEROPLANES Filed May 17. 1928 7Sheets-Sheet @M ,r W

Sept. 10, 1929., L. B, REC 5UET 1,727,696

I AUTOMATIC LANDING BRAKE FOR AEROPLANES 2 Filed May 17, 1928 7Sheets-Sheet 2 Sept. M1), 1929. L. BREGU ET 1,727,696

AUTOMATIC LANDING BRAKE FOR AEROPLANES I Filed May 17, 1928 7Shets-Sheet s Sw-LIW, 19296 L. BREGUET AUTOMATIC LANDING BRAKE FORAEROPLANES Filed May 17 1928 7 SheetsSheet 4 Q. *Q kw Sept. 10, 1929.BREGUET AUTOMATIC LANDING BRAKE FOR AEROPLANES Filed ma 17, 1928 7Sheets-Sheet 5 Sept. 10, 1929. L. BREGUET AUTOMATIC LANDING BRAKE FORAEROPLANES 7 Sheets-Sheet '6 Filed May 17; 1928 b, ni

4 4. f j p 14 I fljf Cpv J W I Sept '10, EQZQU L. BREGUET AUTOMATICLANDING BRAKE FOR AEROPLAQES' Filed May 17, 1928 '7 Sheets-Sheet '7 4 mmulunnnuununnnIn.

IIIIIIIII'IIIIIIIIIIIIII Patented Sept. Ml,

,S TES.

LOUIS BBEGUET, F PARIS, FRANCE, ASSIGNOR TO SOCIETE ANONYME DES ATELIERSDAVIATION LOUIS BREGUET, 01* PARIS, FRANCE, A COMPANY OF FRANCE.

an'roma'rro LANDING BRAKE Fen Annornaiins."

Application filed may 17, 1928, Serial NoJh'TSASO, and in France May19,1927.

The present invention relates to automatic not overturn. It permitsinparticular to" vary the moment of braking when applied to the wheels,eit er proportionally, or according to a given Iunction of the load onthe wheels due to the weight of the aeroplane.-

. In this case, the control of the brake can be connected with theelastic landing device. This connection is constituted in such mannerthat the more the aeroplane is heavy hence the greater the deformationof the elastic landing device, the more powerful is the action of thebrake.

To prevent the aeroplane, from overturning, the brake is operated by theskid or tail,

or by any other element of the aeroplane situated back of the wheels andadapted to ab sorb the perssure ofthe aeroplane on the ground. in suchmanner that the moment of the braking as appliedto the wheels'will increase according to a determined function of the pressure or weight ofthis element upon the ground and will for instance be proportionalthereto.

' The braking becomes less when the aeroplane'connnenees to overturn,the element will bear less on the ground, and the braking ,(Wlll ceasewhen the said element leaves the ground, or when the weight of theelement on the ground attains a determined minimum value.

The braking is thus effected with the maximum security, a progressiveaction, and a perfect continunity.

In fact, while the braking by the air diminishes when the aeroplaneslows up, the braking by the wheels increases since the pressure of theaeroplane on theground increases. The resulting braking is thuscontinuous, and the slowing is efiected rapidly and without suddenvariations. The transmission of'the operations and controls of thebraking to the wheels ofthe aeroplane may be either mechanical orhydraulic.

The-following description with reference to the appended drawings whichare given by way of example will set forth the manner-in which theinvention is carried into'eifect.

Figure 1 shows diagrammatically the braking device which prevents theaeroplane from overturning.

Figure 2 shows diagrammatically a braking device applied towheels-provided with guides. I

Figures-3 and 3 is show an example of the connection between the controlof the brake and the shock-absorbing device of the wheels.

Figures 4 and 5 show a'modification of the 'deviceindicatedin Figure 1.

Figures 6 and 7 are-diagrammatic views showing a devlce permitting toassure on each wheel a braking independent of their load- "andproportional to the differences of the load on the wheels.

Figures 8 and-9 show the arrzingemenhfor each wheel, of a braking whichdepends on its respective load and also on the difference of load onthetwo wheels.

Figure 10 is a diagrammatic longitudinal section of one side of thehydraulic transmissiondevice.

Figure 11 is a diagrammatic crosssection showing the differentialapparatus for equilibrating the pressures in the two transmissions.

Figure-12is a view analogous to Figure 11,

showing a modified form of construction.

Figure 13 is a detail'view of a damping spring for the skid.

The braking devicefor'preventing the areoplane from overturning may beconstructed as shown in Figure 1. i

The skid 1 acts upon the brake 10 by means of the lever 2 which ispivoted at 3, the traction spring 4', the bar 4, the devicefi to befurther mentioned, the bar 5 of. the bell-crank lever 7 pivoted at '8,and the cable 9 attached at 11 which acts upon the shoes of the wheel10. When the skid rests upon the ground. it cocks the spring 4, whichthrough the me dium of the said transmission eatercises trac- 4 frictionupon its shoes.

The said brake may consist of shoes acting with a drum as shown inFigure 1 by way of example, but it may be constructed in any othermanner.

If the weight of the skid diminishes, when the areoplane commences tooverturn, the tension of the spring l diminishes, and the brak-' ingaction of the cable 9 as well; when the skid leaves the ground, thespring 4 is no longer cocked and the braking ceases.

The device 6 permits to neutralize the braking action of the skid whenrising from the ground. This device may be a sort of stretchcrconsisting of a metallic sheath controlled by the pilot by means of ahand wheel 12, and carrying two parts threaded in the con trarydirection into which are screwed the two rods 4: and 5. The said sheaththus permits to increasethe length of the rods i and and hence to expandthe brake controls at will.

The device 6 may be replaced by any suit able device adapted to modifythe total length of the rods 4 and 5. It may also serve to stretch thebrake controls so as to hold the wheels, when it is desired to operatethe motor when the aeroplane is stationary.

Figure 2 shows by way of example, and for the proper understanding, thediagram of the braking device which acts in proportion to the'wcight ofthe areoplane applied to the wheels provided with guides. The axis ofthe wheels is mounted in the member 14 movable in the guides 13. Thecable 9 passes over the pulley 15 whose shaft is secured to the guide13. It acts upon the brake 10, and is attached to a fixed point 16 onthe guide. It is observed that if the weight of the aeroplane on thewheels increases, the'relative motion of the pieces 13 and 14 willincrease the tension of the brake.

, The connection between the brake control and the skid on the one handand the system for damping the wheels on the other hand, may bevariously efiected.

Figures 3 and 3 is show'a form of construction according to thisprinciple in which the braking is proportional to the load upon thewheel and to the load upon the skid or i like element disposed at therear of the aaro plane and subjected to its weight as above specified.in such manner that when the Said skid (or the like) leaves the ground,the braking action ceases. w

The wheel 17 which is loose on the shaft 27 is braked by the disc 18which is slidable without'rotation on'the same shaft and is urged by acompression spring 20 which 11* the weight upon the wheel increases, theelastic cord device will lengthen. and the relative movement of the rackand pinion will screw upon the said shaft the sleeve 21 which thus movesto the left and increases the pressure of the spring 20 which controlsthe braking action 'by pressing the disc 18 against the .wheel.

On the other hand, the disc 18 moves with the skid by means of the rod10. and it is displaced in a direction such that it the skid descends bythe ettect of its reaction spring 81, i. e. if the tail of the aeroplaneleaves the ground, the disc 18 will be moved to the right and thebraking ceases, the action of the spring 31 prevailing over the actionof the spring 20 in all positions of the sleeve 21. The said-device thusallords a braking which is proportional to the weight which is broughtupon the wheels and upon the skid. and which is annulled when the skid,leaves the ground.

To eliminate the braking when the aeroplane rises from the-ground. it issimply necessary to shorten the rod 19. for instance by a device of thetype above described, so to constantly separate the disc 18 trom thesaid wheel, irrespectively ot' the actions of the skid or the wheel.

As a modification, the skid 1 may be replaced by an additional skidprovided with hooks dragging in the ground, which is connccted with thebrake as the skid 1 and is adapted to be released by the pilot at will.

As another modification. the following improvements, which serve toaugment the braking by increasing the weight ot the aeroplane upon theskid, may be combined with the preceding device.

The beam 25 (Figures 4 and which carries the tail, is pivoted on theaxle 23 situated at the rear part of the fuselage. The rear part of thefuselage carries a skid 24: which is connected with the system ofbraking on the wheels and may be provided with a shoe which drags uponthe ground and offers an additional braking effect on the aeroplane. Thebeam 25' is held in its normal position ot flight by a set of elasticcords or like mechanical device. for instance a key which may bewithdrawn when landing, either by the pilot or by the contact with theground.

Wh'en landing. the beam is moved out of action. The shoe 2-llfiikesihcnitipn ot the aeroplane. The moment of action oi the weight around thewheels acting on the shoe 24-. is increased due to the increase of thelcvcr arm (Z resulting from the inclined position o l the aeroplane(Figure 5). The component of the weight of the aeroplane acting upon theskid 21 is greater than it wouldbe it the skid were placed under thetail 26. since the dis tance Z between the skid 2-t and the axis of thewheels is than the distance Z. between the tail 25 and he of saidwheels. The aeroplane wings will have a very great incia device has forits object to prevent the overturning, and also "prevents the aeroplanememes dence, which increases the braking cfiect of the air (Figure 5). i

The rod 19 of Figure 3, or the rod 4 of Figure '1, or any other devicewhich will neutralize the braking, may be controlled either by the skid24 or by the beam 25 in a direction' is proportional to the differenceof the loads on'thewheels and is also proportional to the pressure ofthe skid upon the ground. This from abruptly turning about.

Tnthis case, in fact,-the aeroplane leans tmvards the outside of theturn, thus-loads ing the outer wheel and relieving' the inner wheel. Thebraking device, to be further described,-will prevent this turning, byincreasingthe braking upon the outer wheel and reducing the braking onthe inner wheel.

Figures 6 and 7 are diagrammatic views showing such construction. Thebrake disc 32 partakes of the motion of the skid by means of the cable38,'in a manner resembling what has been specified, and it is alsosubjected to the action of a spring 34: which is compressed by thesleeve35 slidable withoutrotation on the axle 36. j

A horizontal cross-bar or pivoted lever 37 is suspended from astationary frame 39 by means of the pivoted levers 3838 and lS'lIlcontact at its ends with the sleeves 3535.

The bell-crank levers, 38.-38 are respectively connected by thesprings40 40 with the forks 1141 which form, for each wheel,

the movable landing support. If the landing gear of one wheel is subjectto deformation dueato the load upon it occasioned by the weight of theaeroplane (Figure 7), it will actuate the lever 38 and the horizontalcrossbar 37 through the medium of-the traction spring; 410*. The saidcross-bar also exercises a thrust upon the sleeve 3f whose motionproduces a braking of the wheel which is the more energetic as thespring is the more stretched, i. e. as the load on the correspond ingwheel is greater. If the landing devices for the two wheels aresubjeet'ed to equal thrusts and are therefore subjected to a deformationin an equal degree, the two springs 10 and 40? being equally stretched,the crossbar 37 will remain stationary, and the braking will'beindependent of the load on the wheels. in this manner I provide a systemof braking which is proportional to the difference of U the load on thewheels, and the wheel which is the most loaded will alone brake theapparatus. p In the way of a modification of the same general principle,the two Figures 8 and?) show how ll may obtain, for each of the wheels,abraking which is both a function of its respective load and of thedifference of load on the wheels. same, as theone shown in Figures 6and},

with this difference, that the cross-piecei l" no longer acts by thethrust of its'ends on the sleeves 35 and 35 but is connected withthclatter by the links 41 and 41.

Figure 8 shows the left-hand halfof alanding device upon' which theweight of the aeroplane is insuflicient to producethebraking action," inFigure 9 the'right-hand half of the same landing device -is.given, bythe aeroplane, a like thrust upon both wheels,-and the action of'thelinks 40 and 41 causes thesleev'e 35 and 35 to slide on the axle inorder to-exerc'ise an equal braking action upon both wheels. V a

If one of the'wheels ismore-heavily loaded than the other, the actionofthe cross bar 37 will intervene as-in the'case of Figures 6 and 7.This will allord a braking whichjde pends upon the respective load uponeach wheeland upon the difference between ,the loads upon each wheel. J1 I I Figure 10 is a diagrammatic view showing an example, of a devicefor thehydraulio COIlf The said device is the trol of the braking uponthe wheels which varies in the same direction as the weight of theaeroplane on its strut, which depends up,- on the difference of the loadupon the two wheels of the aeroplane, it being operated 'at' the will ofthe pilot.

The brake is of the band type; A'band 101 which is attached at one-endto a fixed point103 on the fork 10st is pressed upon the drum 105 ofthewheel102 by a suitable dis placement of its other end which isobtained by a piston 106slidable in a'cylinder 107 secured to thelanding device. The said piston'106 moves under the action of the pressure of the liquid contained in the cylinder, which is opposed by theaction of aspring 109.

The general piping 108 is connected with the cylinder 107 by a flexiblehose 110 which provides for the displacement of the wheel when thelanding gear is subject to deformation. The piping 108 is. connected bya branch pipe with. a differential cylinderlll (to be furtherdescribed), with a controlling cylinder 112 placed within the pilotsreach and with a cylinder 113 forming part of a device controlled by theskid.

the liquid, but they are joined through the llO medium of the mechanicalpart of the skid and of the differential device 111.

The cylinder. 111 contains a piston 123 (Figure 11) separating theliquids of the pipes. 108 and 108. The displacement of this piston,limitedby the stops 125 and 125, depends upon the differences of theload of the aeroplane on the wheels.

For this purpose, the rods 127 and 12-7* of this piston are connectedrespectively by the elastic cord devices 12 1 and 12 1 with thebell-crank levers 126 and 126*. Each of these levers is displacedtogether with the fork of the corresponding landing device.

If the loads on the wheels are equal, the strokes of the forks are alsoequal, and the cords 12 1 and 12 1 will be stretched to an equal degreeand hence will not act on the piston 123; if the loads on the wheelsdiffer, the piston is drawn to the side next the most heavily loadedwheel.

In the piston 113 is slidable a piston 114 acted upon by a compressionspring 115 which is cooked by means of a bell-crank lever 116 which iscontrolled by the rod 117 said rod carries at the lower end a boxcontaining a spring 119 serving as a shock-absorber for the .skid 120/The stroke of the box 118 is limited by its contact with the frame 121.The rod.117 is this limited in its displacements by this stop and thestop 130.

The spring 119 perrhits the skid to havea greater amplitude, withoutmodifying its action on thebraking parts, which action is limited tothat obtained when the box 118 is in contact with its cage. The saidstops as well as the stops 125 and 125 may be adjustable. They permit tolimit the action of the brakes to a maximum, to avoid blocking thewheels during landing. r

The volume of liquid in the piping 108 of the cylinders 107, 112 and114; and the left hand half of the cylinder 111 is constant.

of like parts.

The same is true for the'circuit for the braking of the right handwheel, which consists For this reason, by operating by the lever 122 thepiston. 121 coacting with the cylinder 112, the pilot can, as desired,act upon the pistons 106 and 11 1 through the medium of the column ofliquid, and he may compress the springs 109 and 1.15.

The pilot may eflect, with this device, the following controls p1.-vVhen the aeroplane is stationary, he may block the wheels by drivingdown the piston 121 so as to send into the pipe 108 the liquid of thecylinder 112 and fill the cylinders 107 and 118, and thus compress thesprings 108 and 115. The brake will be thrown with more energy accordingas the pressure of the piston 121 on the liquid, i. e.

2.-When rising, he can obviate all possivbility of braking, whatever maybe the action of the skid and the loads on the wheels, by drawing up thepiston 121 in such manner as to draw into the cylinder 112 the liquidcontained in the cylinders 107 and 113.

3.lVhen travelling on the ground, he may turn about with greaterfacility by eliminating the braking on the outer wheel in the turn bythe said means, and by braking on the inner wheel of the turn bycontrolling by the corresponding lever.

4.During flight, he may prepare the apparatus for braking as soon as theskid makes contact with the ground, by placing the piston 121 at a givenposition so as to send into the piping the volume of liquid necessary tobring the piston 100 to a position near the braking position, and therod of the piston 114: into contact with the spring 115, but withoutgiving any tension to this spring.

Upon landing, the skid will bend under the weight of the aeroplane andit thus compresses the spring 119 which pushes the rod 117, and due tothe lever 116-cocks the spring 115; the piston 11 1 now moves, and itsends liquid into the piping 108 until the piston' 106 is at the end ofthe stroke, the' brake band being pressed upon the drum. Upon thetension of the spring 115 will depend the braking effort; this latterthus varies with the load on the aeroplane, with a. n'iaxinium which isattainedwhen the box 118 makes contact with the stop.

. The operation as described for the left hand wheel is the same for theright hand wheel.

If the loads on the two wheels are equal, I

pistons 106 are both at the end of the stroke in the braking position,any movement of the piston 123 will correspond to displacements of thepistons 114 and 1141 in the other direction, and also to -differenttensions of the'springs and 115. The most loaded wheel will be morestrongly braked, and the least loaded wheel will be less stronglybraked.

WVhen the skid spring 115 can now expand; this expansion causes a fallofpressure in the pipe 108, and the brakes are thrown off. The bores ofthe cylinders 107111113, the strokes of the pistons 106114r123, and thepositions of the stops 125 and 125, are so dete anined thatthe volume ofliquid entering the cylleaves the. ground, the

inder 113, when the skid rises from the ground, will always be greaterthan that due to the cylinder 111. It will result that whatever may bethe'brakingaction due to the wheels, the braking will be annulled assoon as the skid rises from the ground, or by changing the tension ofthe spring 115 for example as soon as the weight of the aeroplane on theskid attains a determined minimum value. I

This arrangement of hydraulic control is susceptible of variousmodifications permitting to realize the difierent cases above specifled,and in particular, a braking which depends upon the load on the wheelsinstead of the difierence of load on the wheels. In this case, thedevice 111 of Figs. 10 and 11 is eliminated.

The two systems "for braking the wheels are separate, and each comprisesa cylinder 131 or 131 adapted to replace the cylinder 111, as shown inFigure 12.

In the cylinder 131, connected with the pipe 108, is slidable a piston132 which is actuated by a pivoting lever 134 through the medium of acompression spring 133. The lever 134 is actuated by the box 135slidable in a frame 136 and containing the damping spring 137 of thelanding fork 136.

The disposition of the parts and their operation are the same as thoseof the skid. The pressure of the oil obtained by the displacement of thewheel is proportional to the load of the aeroplane on the latter and islimited toa maximum when the box 135 makes contact with its frame 138.By replacing the lever 134 by a cam having a suitable outline, such asthe cam 139 represented for the right hand wheel of Figure 12, I mayobtain a braking eliect which is a more. or less complex each mountedupon an axle secured to a member vertically slidable ina guide, a skidpivoted upon an-axle mounted on the aeroplane, a lever in operativeengagement with said skid, a vcable connection between said lever andthe individual brakes of the wheels, a

hand control for the said cable connection, a

sleeve mounted on the axle of each wheel, a spring interposed betweensaid sleeve and the distance of rolling on the ground, said system.comprising in combination, individual brakes upon the wheels, saidwheels being each mounted upon an axle secured to a member verticallyslidable in a guide, a skid pivoted upon an axle mounted on theaeroplane, a lever in operative engagement with said skid, a cableconnection between said lever and the individual brakes of the wheels, ahand control for the said cable connection, a sleeve mounted on the axleof each wheel, a spring interposed between said sleeve and the brakeshoe, a pivoted cross-bar connected with the sleeves of the two Wheels,said crossbar being suspended from the arms of two bell-crank levers,and springs of like construction connecting the other two arms with thewheel axle.

3. A system for braking upon the wheels of aeroplanes, which is adaptedto reduce the distance of rolling on the ground, said system comprisingin combination, individual 7 brakes upon the wheels, said wheels beingeach mounted upon an axle secured to a member vertically slidable in aguide, a skid pivoted upon an axle mounted on the aeroplane, a leverinoperative engagement with said skid, a cable connection between saidlever and the individual brakes of the wheels, a hand control for thesaid cable connection, a

sleeve mounted on the axle of each wheel, a spring interposed betweensaid sleeve and the brake shoe, a pivoted cross-bar connected with thesleeves of the two wheels, said crossbar being suspended from the armsof two bell-crank levers, and springs of like construction connectingthe other-two arms with the wheel axle, a link pivoted to each end ofthe said cross-bar and to the corresponding sleeve.

In testimony whereof I have signed this specification.

LOUIS BREGUET.

brake shoe, said sleeve being slidable on the 'axle of the wheel.

2. A system for braking upon the wheels of aeroplanes, which is adaptedto reduce the

